PROJECT SUMMARY Sleep deficiency, which includes sleep deprivation, sleeping at the wrong time of day, or poor quality of sleep, may affect OUD treatment engagement and retention among people recently released from jail. Sleep deficiency may lead to biologic, psychiatric, and pharmacologic mechanisms, such as stress, negative affect, pain or other substance use that may increase the likelihood of illicit opioid use, and disengagement in OUD treatment. Further, release from incarceration may increase sleep deficiency. Incarcerated people are more likely to witness and directly experience trauma which can, in turn, affect sleep health by causing nightmares, insomnia, sleep apnea, and general sleep disruption. Release from incarceration can cause significant disruptions in sleep habits. In jails, people are often subjected to sleeping in environments where lights, noise, and schedule are out of their control or where they are medicated to sleep. Changes from that environment may create difficulties with sleep. Our long-term goal is to reduce morbidity and mortality from OUD among justice-involved individuals. The overall research objective of this supplement is to examine the association between sleep deficiency and OUD treatment retention in a sample of people receiving medications for OUD (MOUD) who were recently released from jail. This proposal brings together the expertise of two HEAL-funded grants at Yale School of Medicine, [5UG1DA050072-02-JCOIN, Transitions Clinic Network: Post Incarceration Addiction Treatment, Healthcare, and Social Support (TCN PATHS) and 1U01HL150596-01- The CLOUDS Study], both aimed at understanding and improving MOUD engagement and retention. The central hypothesis of this supplement is that sleep deficiency is associated with worse OUD treatment retention and that sleep environment is a novel mediator of this association. The underlying rationale for this study is that sleep deficiency must be addressed in a holistic manner to support OUD treatment engagement. We aim to: (1) Determine the prevalence of sleep deficiency and describe the sleep environment of a sample of people on MOUD recently released from jail; (2) Estimate the association between sleep deficiency and OUD treatment retention; and (3) Examine sleep environment as a potential mediator of sleep deficiency and OUD treatment retention in people recently released from jail. To achieve these aims, participants from two TCN PATHS sites (n=220) will complete the Pittsburg Sleep Quality Index (PSQI) and wear a device on their wrist (Actiwatch) that will record data on the participant?s sleep environment and ambient light during sleep. Additionally, we will use neighborhood-level noise and light data from the National Transportation Noise Map and the Centers for Disease Control and Prevention to describe participants? sleep environment. We will measure OUD treatment retention at 1,3, and 6-months post release. This study will provide data for the future development and testing of patient-centered interventions focusing on sleep deficiency among OUD treatment participants that enhance their retention in treatment.